Dual-fuel engine systems for work vehicle

Abstract

A dual-fuel engine system for a work vehicle includes an engine with a piston-cylinder arrangement defining a combustion chamber and an engine control unit (ECU). The ECU has a processing and memory architecture configured to execute instructions to deliver to the engine only a first fuel when an operating load of the engine is less than 5 a first predetermined threshold, deliver only a second fuel and operate the engine stoichiometrically when the operating load is greater than a second predetermined threshold. The second predetermined threshold is greater than the first predetermined threshold.

What is claimed is: 
     
       1. A dual-fuel engine system for a work vehicle, comprising
 an engine being a compression ignition engine with a piston-cylinder arrangement defining a combustion chamber; 
 an engine control unit (ECU) having a processing and memory architecture configured to execute instructions to deliver to the engine only a first fuel when an operating load of the engine is less than a first predetermined threshold, deliver only a second fuel and operate the engine stoichiometrically when the operating load is greater than a second predetermined threshold, wherein the second predetermined threshold is greater than the first predetermined threshold; and 
 an aftertreatment system disposed in an exhaust flow path between the engine and an exhaust vent, wherein the exhaust flow path is free of any injected catalytic reductant. 
 
     
     
       2. The dual-fuel engine system of  claim 1 , wherein the ECU delivers a combination of both the first fuel and the second fuel when the operating load is between the first predetermined threshold and the second predetermined threshold. 
     
     
       3. The dual-fuel engine system of  claim 1 , wherein the aftertreatment system comprises one or both of a three-way catalyst and a particulate filter. 
     
     
       4. The dual-fuel engine system of  claim 3 , wherein the exhaust flow path is free of a selective catalytic reduction device. 
     
     
       5. The dual-fuel engine system of  claim 1 , further including fuel injector assemblies, wherein the ECU selectively operates the fuel injector assemblies to deliver only the first fuel, the second fuel, or both the first and the second fuels to the engine. 
     
     
       6. The dual-fuel engine system of  claim 5 , wherein when the operating load is greater than the second predetermined threshold, the ECU operates a fluid injection device to add a non-combustible fluid to the second fuel and operates the fuel injector assemblies to deliver a mixture of the non-combustible fluid and the second fuel to the combustion chambers of the engine. 
     
     
       7. The dual-fuel engine system of  claim 5 , wherein the non-combustible fluid comprises water. 
     
     
       8. The dual-engine system of  claim 1 , wherein the first fuel is one of biodiesel, renewable diesel, dimethyl ether, ether, or fossil diesel. 
     
     
       9. The dual-engine system of  claim 1 , wherein the second fuel is an alcohol based or an alcohol diluted with water. 
     
     
       10. An engine control unit (ECU) for a work vehicle having a dual-fuel engine system having an engine being a compression ignition engine comprising a piston-cylinder arrangement defining a combustion chamber and an aftertreatment system disposed in an exhaust flow path between the engine and an exhaust vent of the work vehicle, the ECU comprising:
 a controller having a processing and memory architecture configured to execute instructions according to an operating load of the engine to deliver to the engine only a first fuel when the operating load is less than a first predetermined threshold, deliver to the engine only a second fuel and operate the engine stoichiometrically when the operating load is greater than a second predetermined threshold, wherein the second predetermined threshold is greater than the first predetermined threshold; 
 wherein the exhaust flow path is free of any injected catalytic reductant. 
 
     
     
       11. The ECU of  claim 10 , wherein the controller delivers to the engine a combination of both the first fuel and the second fuel when the operating load is intermediate the first predetermined threshold and the second predetermined threshold. 
     
     
       12. The ECU of  claim 10 , wherein a cetane value of the first fuel is greater than a cetane value of the second fuel. 
     
     
       13. The ECU of  claim 10 , wherein the aftertreatment system comprises one or both of a three-way catalyst and a particulate filter. 
     
     
       14. The ECU of  claim 13 , wherein the exhaust flow path is free of a selective catalytic reduction device. 
     
     
       15. The ECU of  claim 10 , further including fuel injector assemblies, wherein the ECU selectively operates the fuel injector assemblies to deliver only the first fuel, the second fuel, or the first and the second fuels to the engine. 
     
     
       16. The ECU of  claim 15 , wherein when the engine load is greater than the predetermined threshold, the ECU operates a fluid injection device to add a non-combustible fluid to the second fuel and operates fuel injector assemblies to deliver a mixture of non-combustible fluid and the second fuel to the engine. 
     
     
       17. The ECU of  claim 10 , wherein the first fuel is one of biodiesel, renewable diesel, dimethyl ether, ether, or fossil diesel. 
     
     
       18. The ECU of  claim 10 , wherein the second fuel is an alcohol or an alcohol diluted with water.